1. Field of the Invention
The present invention relates to a polyolefin resin composition and to a molded article obtained by molding the composition. More particularly, the invention relates to a polyolefin resin composition which has good appearance and excellent mechanical strength and, in addition, is superior in long-term durability of mechanical strength, for example, superior in thermal degradation resistance, light stability and copper-accelerated thermal degradation resistance which persist for a long term in the environment with influence of oxygen, heat and light. The invention also relates to a molded article obtained by molding the composition.
2. Description of the Related Art
Polyolefin resin is widely used as general purpose resin in various fields because it is superior in mechanical strength, heat resistance, mold ability, chemical resistance, etc and also because it is a relatively inexpensive polymeric material. In particular, replacement of polymeric materials such as ABS, nylon and polycarbonate, which have been used in the fields of automotive components and household electric appliances, by polyolefin resin, especially polypropylene resin has recently been going on.
As one example of polypropylene resin composition for use in the fields of automotive components and household electric appliances, Japanese Patent Application Publication No. 6-279630 discloses a colored polypropylene composition superior in heat aging resistance, namely, a heat aging resistant colored polypropylene composition comprising acetylene black or a perylene-based black pigment in polypropylene.
Japanese Patent Application Publication No. 10-176085 discloses a glass fiber-reinforced polypropylene resin composition having good appearance and moderate mechanical strength, specifically, a glass fiber-reinforced polypropylene resin composition comprising maleic anhydride-graft-modified propylene-based polymer and glass fiber treated with a silane coupling agent.
The polypropylene resin compositions disclosed in the publications of patent applications have appearance and mechanical strength improved to some extent. There, however, is a demand for further improvement in long-term durability of mechanical strength, for example, thermal degradation resistance, light stability and copper-accelerated thermal degradation resistance which persist for a long term, in the environment with influence of oxygen, heat and light.